CAUGHT: Police surround Gregory John Thompson's car outside Michael Moad's house in Cessnock on March 1, 2015. This week Mr Thompson was sentenced for the killing.

A MAN who brutally stabbed his ex-wife's new boyfriend to death in the victim's own home has been sentenced to more than 23 years jail.

Newcastle Supreme Court Justice Peter Hamill also declared on Thursday that Gregory John Thompson would spend at least 17 years and seven monthsbehind bars before he is eligible for parole.

A jury found Thompson guilty on Tuesday of the brutal murder of Michael Moad after after a nine-day trial and just four hours of deliberations.

Thompson, 51, of Nulkaba, had pleaded guilty to manslaughter on the first day of his trial, admitting he was responsible for stabbing Cessnock man Michael Moad 10 times in the laundry of Mr Moad’s Edgeworth Street home in the early hours of March 1, 2015.

But he had pleaded not guilty to murder, raising a partial defence of substantial impairment by way of “abnormality of the mind” due to an underlying condition, which he said affected his capacity to either understand events, judge right from wrong or control himself at the time of the killing.

The key issue in the trial was Thompson's mental state around the time of Mr Moad's horrific death, with the jury ultimately rejecting defence claims that he was substantially impaired by a major depressive illness.

The jury had previously heard that the stabbing followed years of psychological abuse, a messy divorce and escalating tensions between Thompson and his ex-wife, Karen Thompson.

Thompson had been arrested twice in two days in the lead-up to the murder – once for harassing his ex-wife and then for following her and Mr Moad and breaching an apprehended violence order.